Device for increasing the security of a motor vehicle

ABSTRACT

The invention relates to a device for increasing the security of a motor vehicle comprising an automatic transmission, which is impinged upon by an electrical transmission control system and a detection unit for detecting a critical driving situation and for generating a corresponding signal. In order to increases driving security, an evaluation device is provided which checks whether the generated signal has reached a specific value or exceeded a specific threshold. If said value has been reached or the threshold has been exceeded, the evaluation device causes the transmission control system to interrupt the positive engagement of the transmission.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a device for increasing the security of avehicle, and, more particularly, to a device for increasing the securityof a vehicle having an automatic transmission, which is acted upon by anelectric transmission control and a detection device for detecting acritical driving situation and generating a corresponding signal.

If it is determined that vehicle security is at risk, measures shouldgenerally be taken for continuously ensuring the vehicle security. Inthe following, a differentiation will be made between two groups ofsituations with respect to the vehicle security.

On the one hand, vehicle security may relate to a stable vehiclehandling. Many methods and systems for improving the directional controlare known.

For example, from German patent document DE 196 35 809 A1, a method anda system are known for improving directional control in the coastingoperation, in which the transmission line is interrupted by disengaginga friction clutch when the difference of the rotational wheel speedsbetween the driven and non-driven wheels exceeds a certain thresholdvalue. As a result, the directional control is increased in the coastingoperation.

From German patent document DE 35 28 389 A1, a corresponding system isknown for a wheel slip control.

U.S. patent document U.S. Pat. No. 5,362,287 describes a control methodfor an automatic clutch in the case of which the transmission line isinterrupted when an excessive wheel slip is detected, the wheel slipbeing the result of an engine braking.

In the case of automatic transmissions, it is also recommended that,when the vehicle handling is unstable or during a swerving event, the“neutral” transmission position be engaged manually in order to morerapidly return the vehicle into a stable condition. However, very fewdrivers are capable of removing a hand from the steering wheel during aswerving event and moving the gear selector lever to the N position.

Another group of situations is represented by driving situations in thesense of accident situations. In accident situations, it is generallyprovided that, for safety reasons, a vehicle is to be stopped after anaccident and any further vehicle movement is to be avoided.

For solving this problem various measures are known. For example, it ispossible to interrupt the ignition or the fuel supply after an air bagis triggered, which may be used as an indicator with respect to anaccident. The engine is then switched off after a corresponding event.However, it is also possible to interrupt the vehicle movement in atime-delayed manner. Furthermore, there is the risk that a disturbanceexists in the engine timing unit and/or there is an interference in thesignal transmission from the air bag control unit to the engine timingunit.

Furthermore, an air bag control unit is known from Japanese patentdocument JP 10103498, which provides a signal to a transmission controlwhen an air bag is triggered. When the air bag is triggered, thetransmission control shifts the transmission into a state with a lowtorque output.

It is an object of the present invention to further develop a system ofthe above-mentioned type for increasing the security in the case of avehicle in order to ensure the vehicle safety in every case also duringaccidents and swerving events.

This object is achieved by a device for increasing the security of avehicle having an automatic transmission, which is acted upon by anelectric transmission control, and a detection device for detecting anaccident or a swerving event and generating a corresponding signal. Ananalyzing device is provided to examine whether the generated signalreaches a certain value or exceeds a certain threshold. When the valueis reached or the threshold is exceeded, the analyzing device causes thetransmission control to interrupt the positive engagement of thetransmission.

An essential idea of certain preferred embodiments of the presentinvention is the fact that the positive engagement in the transmissionwill be interrupted when a detection unit determines an accident or aswerving situation.

According to a first embodiment of the invention, the positiveengagement in the automatic transmission will be interrupted by theelectric transmission control in the event swerving starting at adefined swerving intensity. In a preferred embodiment, the transmissionwill then be shifted into the neutral position. In this manner, it ispossible to interrupt the positive engagement in the transmission lineindependently and in the required manner in order to ensure highdirectional control of the vehicle.

According to an alternative embodiment of the invention, thetransmission is controlled by the electric transmission control in theevent of a triggering of an air bag and/or a rollover event such thatthe positive engagement in the transmission is interrupted. As a result,it is ensured that continued movement of the vehicle will be preventedeven if the engine continues to run. In this case, the triggering of anair bag or the rollover event are used as an indication of theoccurrence of an accident. A conclusion can be drawn with respect to thetriggering of an air bag either by way of monitoring a crash sensordirectly or by way of the reaction of an air bag control unit. In thissense, a triggering of an air bag is assumed even when signals aredetected which lead to a triggering of an air bag.

In the above context, an embodiment of special interest is in the casewherein an automatically operable parking position is provided, which isalso addressed by a control unit and which will be engaged when thevehicle has come to a stop after an air bag triggering operation and/ora rollover event. For indicating and including the vehicle speed, anormally existing vehicle speed sensor can be analyzed. Naturally, theparking position can also be engaged on the basis of other criteria.Furthermore, it is possible to immediately engage the parking positionwhen the positive engagement is interrupted because of the air bagtriggering operation or the rollover event. In this context, referenceis also made to German patent document DE 196 25 019 A1 in which, amongother things, an automatic activating of the parking position isdescribed. By activating the parking position, rolling-away iseffectively prevented after a stoppage of the vehicle.

According to another preferred embodiment, a transmission selectiondevice is provided which has a defined rest position and, for selectinga driving position desired by the driver, can be directed out of itsrest position into which it will then automatically return. When thepositive engagement is interrupted or a shifting into the neutralposition takes place on the part of the transmission, the driver willnot be confused by different adjustments of the transmission selectiondevice, on the one hand, and of the transmission, on the other hand.Also, no synchronization problems occur as a result of absent detentpositions.

Additional embodiments are defined in the subclaims.

Two simple embodiments of the present invention will be explained indetail with respect to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a device for increasing thedirectional control according to the invention; and

FIG. 2 is a schematic block diagram of a second embodiment of the deviceaccording to the invention for increasing the security.

DETAILED DESCRIPTION OF THE DRAWINGS

According to FIG. 1, an internal-combustion engine 12, which is coupleddirectly with a transmission 10, is arranged in a vehicle which is notshown. An output shaft 14 extends from the transmission 10 in thedirection of the wheels which are not shown.

The transmission is an automatic range transmission which is shifted bymeans of an electric transmission control 16. The transmission control16 receives its input information from a bus 18 (such as a CAN bus). Ithas an interface which is not described in detail and which is coupledwith the bus 18 (reference number 20) and which filters the requiredinformation out of the information present on the bus.

In the first embodiment, information concerning rotational wheel speedsN₁ to N₄ is present on the bus 20, which is fed into the bus 18 bycorresponding rotational wheel speed sensors 22 to 28. In addition,information concerning the yaw rate G is present on the bus 20, whichyaw rate G is fed by a yaw sensor 30.

The electric transmission control 16 continuously determines a swervevalue from the signals N₁ to N₄ and G and compares this swerve valuewith a limit value stored in the transmission control 16. If the swervevalue exceeds the defined limit value, the transmission 10 shifts intoits neutral position whereby the positive engagement in the transmissionline is interrupted.

As an alternative, the signals of other sensors or detection deviceswhich permit a conclusion with respect to a swerving event can naturallyalso be analyzed.

In certain critical situations in which an interruption of thetransmission line is helpful, the driver must therefore no longermanually shift the transmission into the neutral position. On thecontrary, this is carried out by the vehicle itself.

An alternative embodiment of the invention is illustrated in FIG. 2. Inthis case, an internal-combustion engine 112 is arranged in a vehicle,which is also not shown. This internal-combustion engine 112 is againdirectly coupled with a transmission 110. An output shaft 114 extendsfrom the transmission 110 in the direction of the wheels which are notshown.

The transmission 114 is an automatic range transmission which is shiftedby means of an electric transmission control 116. The transmissioncontrol 116 receives its input information from a bus 118. Thetransmission control 116 has an interface 120 which is not described indetail and which is coupled with the bus 118 and filters the requiredinformation out of the information present on the bus 118.

In a second embodiment, information concerning air bag triggeringevents, specifically signals AN₁ to AN₄, are present on the bus 120.These signals are fed by corresponding air bag triggering devices 122 to128, for example, crash sensors or an air bag control unit, into the bus118. Furthermore, information concerning a rollover event Ü is presenton the bus 120, which information is fed by a rollover sensor 130.

The electric transmission control 116 now continuously monitors theexisting air bag triggering and rollover signals. When a triggering ofan air bag or a rollover event is detected, the transmission 110 isshifted such that its positive engagement is interrupted. Thus, no moretorque is transmitted from the engine 112 to the driving wheels and acontinued movement of the vehicle is effectively prevented.

As an alternative, naturally the signals of other sensors or detectiondevices can also be analyzed, from which a conclusion can then be drawnwith respect to a situation in which the positive engagement in thetransmission should be interrupted.

In critical situations in which an interruption of the positiveengagement in the transmission line or in the transmission is helpful,the driver therefore no longer has to manually shift the transmissioninto the neutral position. On the contrary, the vehicle itself achievesan interruption of the transmission line and, as a further development,a locking of the wheels.

Another embodiment of the invention includes the previously discussedgear selection device for selecting a driving position desired by thedriver, having a rest position to which the device automatically returnsafter the driver selects the desired driving position. As shown in FIG.1, gear selection device 32 provides a driving position input to thetransmission control 16. Alternatively, the driving position input maybe indirectly routed from gear selection device 32 to transmissioncontrol 16, for example, through bus 18.

Since the above-mentioned applications can be implemented by acorresponding modification of the transmission software, a particularlycost-effective implementation is possible.

1. A device for increasing security of a motor vehicle, comprising: anautomatic transmission; an electric transmission control operativelycoupled with the automatic transmission; a detection device that detectsa parameter of one of an accident and swerving event of the vehicle andgenerates a signal corresponding to the parameter; an analyzing devicethat evaluates whether the signal reaches a specific value or exceeds aspecific threshold corresponding to presence of the accident or swervingevent, said analyzing device causing the electric transmission controlto interrupt a positive engagement of the automatic transmission byshifting the automatic transmission into a neutral position when thespecific value is reached or the specific threshold is exceeded.
 2. Thedevice according to claim 1, wherein the detection device is part of anair bag triggering device, said analyzing device causing theinterruption of the positive engagement when a triggering of an air bagor a signal that leads to the triggering of the air bag is detected. 3.The device according to claim 2, wherein the part of the air bagtriggering device comprises at least one of a crash sensor and an airbag control unit that provides signals used for triggering the air bag.4. The device according to claim 3, wherein the detection device alsoincludes a rollover sensor, the positive engagement being interruptedwhen a rollover event is detected.
 5. The device according to claim 3,further comprising an automatic parking position system, said automaticparking position system being activated when the positive engagement ofthe transmission is interrupted.
 6. The device according to claim 2,wherein the detection device also includes a rollover sensor, thepositive engagement being interrupted when a rollover event is detected.7. The device according to claim 2, further comprising an automaticparking position system, said automatic parking position system beingactivated when the positive engagement of the transmission isinterrupted.
 8. The device according to claim 7, further comprising avehicle speed sensor, said automatic parking position system beingactivated when, in addition to the interruption of the positiveengagement, the vehicle speed is substantially zero.
 9. The deviceaccording to claim 1, wherein the detection device is a rollover sensor,the positive engagement being interrupted when a rollover event isdetected.
 10. The device according to claim 9, further comprising anautomatic parking position system, said automatic parking positionsystem being activated when the positive engagement of the transmissionis interrupted.
 11. The device according to claim 1, wherein thedetection device generates a value describing the swerving event, saidanalyzing device causing the interruption of the positive engagement ofthe transmission when the swerving event value exceeds a specificthreshold value.
 12. The device according to claim 11, wherein thedetection device includes at least one of rotational wheel speed sensorsand a yaw rate sensor.
 13. The device according to claim 1, wherein thedetection device includes at least one of rotational wheel speed sensorsand a yaw rate sensor.
 14. The device according to claim 1, wherein saidanalyzing device is integrated into the electric transmission control.15. The device according to claim 1, further comprising a gear selectiondevice having a defined rest position, said gear selection device beingdirected out of the rest position in order to select a driving positiondesired by the driver and then being automatically returned.
 16. Amethod for increasing security of a vehicle having an automatictransmission operatively coupled with an electric transmission control,the method comprising the acts of: detecting one of an accident and aswerving event of the vehicle; generating a signal value associated withthe accident or swerving event; evaluating the signal value to determinewhether it reaches a specific value or exceeds a specific threshold; andinterrupting the positive engagement of the automatic transmission byshifting the automatic transmission into a neutral position when thespecific value is reached or the specific threshold is exceeded.
 17. Themethod according to claim 16, wherein the act of detecting the accidentis carried out by determining whether an air bag is triggered or whethera signal leading to the triggering of the air bag is detected.
 18. Themethod according to claim 17, further comprising the act of activatingan automatic parking position system when the positive engagement of thetransmission is interrupted.
 19. The method according to claim 16,wherein the act of detecting the swerving event is carried out byanalyzing signals from at least one of rotational wheel speed sensorsand a yaw rate sensor of the vehicle.